Depending on the sports application being considered, a user can greatly benefit from using a wearable device, for instance, for training or performance analysis purposes. One key aspect in such applications is to allow the user to easily interact with the device with no or only a minimal amount of interferences with the performed sports activity. Such interferences may for instance induce a loss of concentration or a break in the flow of the performed sports activity, in either way resulting in lesser performance and efficiency in the performed sports activity. Known user input technologies in electronic devices such as for instance buttons or touch screens are not well suited in most sports applications as they require the user to focus their attention on the device to perform an interaction (for example by searching a button with a finger and/or directly looking at the device to actuate a touch screen). Furthermore, the required compactness and miniaturization of the device to achieve good ergonomics and not to physically hinder natural movements only amplify these difficulties. In certain sports applications these interactions may become even more complicated. For example, in sports applications where the user is holding or wearing pieces of sports equipment (for instance a racket in tennis, a club in golf or gloves in ice hockey), the interactions are awkward or even require releasing or removing pieces of sports equipment. More generally, in most sports applications these interactions require a drastic change of stance to operate the device compared to when performing the sports activity. The disclosed invention solves these drawbacks by using motion based interactions to operate the wearable device.
A major challenge when using motion based user interfaces in sports applications is to find a robust mean to discriminate seamlessly between normal sports activity movements and specific interaction movements with the wearable device. If not correctly addressed, this issue can greatly limit or jeopardize the usability of the motion based user interface in sports applications. Previously disclosed motion based interaction devices and methods, for instance in the fields of remote controls, input devices or gaming interfaces, cannot robustly and efficiently be used in sports applications as they cannot prevent false user inputs being detected by the device (false positives) in the middle of a movement intensive task and/or rely on the user to perform an enabling or triggering action prior to motion recognition. Examples of prior art in remote control, input device or game control fields include a segmentation step that tries to identify a gesture sequence between user triggers (for instance a button pressing) or moments of inactivity. The segmented movement sequence is processed by a gesture recognition method that determines a matching user input (for instance command or information). Other prior art examples introduce the enabling or the extension of the number of available input commands depending on measured sensor values while using additional sensor values to monitor the input movement (for instance defining different spatial planes in which input movements are enabled or represent different input commands). These methods although applicable to their respective fields are either too limiting or unsuited in sports applications where continuous and unpredictable movements are experienced by the device. Examples for devices hardly suitable for scoring use during active sports are U.S. Pat. No. 8,010,911, US-A 2012/0016624, US-A 2011/0205156 and US-A 2013/0002538.